Haha. This video must be assembled by some kind of an AI. The kastro part presents aerial map of the Kastro in Sifnos which is in a completely different island, the following video material is from the ruins of Apano Kastro, Naxos and the AI voice is talking about the actual Venetian Kastro of Naxos.
I visit Naxos Ios and Santorini. Naxos is definetyly no. 3. Nothing interesting and beautifull is there in my opinion. I can recommende Santorini, one o the most beautiful places i ever seen.